Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!ames!rex!hoang
From: hoang@rex.cs.tulane.edu (Dzung Hoang)
Newsgroups: sci.electronics
Subject: Re: Substituting Caps oin Logic Supplies
Message-ID: <814@rex.cs.tulane.edu>
Date: 26 May 89 03:56:25 GMT
References: <484@dalek.UUCP> <1989May24.154332.29113@utzoo.uucp>
Reply-To: hoang@rex.UUCP (Dzung Hoang)
Organization: Computer Science Dept., Tulane Univ., New Orleans, LA
Lines: 43

In article <1989May24.154332.29113@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
>In article <484@dalek.UUCP> sjb@dalek.UUCP (Seth J. Bradley) writes:
>>... The question is, are the new ultra-high caps
>>(i.e. 3.3F at 5.5 V) which are designed for power backup
>>suitable for use as power supply filter capacitors?
>
>In general, no -- their internal resistance is too high.  Substantial
>currents flow in and out of filter capacitors during the AC cycle.
>-- 
>Van Allen, adj: pertaining to  |     Henry Spencer at U of Toronto Zoology
>deadly hazards to spaceflight. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

To: henry@utzoo.uucp
Subject: Re: Substituting Caps oin Logic Supplies
Newsgroups: sci.electronics
In-Reply-To: <1989May24.154332.29113@utzoo.uucp>
References: <484@dalek.UUCP>
Organization: Computer Science Dept., Tulane Univ., New Orleans, LA
Cc:
Bcc:

In article <1989May24.154332.29113@utzoo.uucp> you write:
>In article <484@dalek.UUCP> sjb@dalek.UUCP (Seth J. Bradley) writes:
>>... The question is, are the new ultra-high caps
>>(i.e. 3.3F at 5.5 V) which are designed for power backup
>>suitable for use as power supply filter capacitors?
>
>In general, no -- their internal resistance is too high.  Substantial
>currents flow in and out of filter capacitors during the AC cycle.
>--
>Van Allen, adj: pertaining to  |     Henry Spencer at U of Toronto Zoology
>deadly hazards to spaceflight. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

    Uh, high internal resistance is desirable in capacitors.  I really doubt
that much AC current will flow through the capacitor if it is used as a power
supply filter.

    You should have no problem if the DC voltage is less than 5V, although
3V or so would be better.  These caps can be easily damaged by apply too-
high voltages.  Try it and see.

Dzung Hoang
hoang@rex.cs.tulane.edu